Window sash balance



March 10, 1953 G. STEINGRUBER WINDOW SASH BALANCE 3 Sheets-Sheet 1 FiledAug. 17, 1948 INVENTOR.

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3 Sheets-Sheet 2 G. STEINGRUBER WINDOW SASH BALANCE 1N.VENTOR.

March 10, 1953 Filed Aug.

- 0 m @N Nu? N 0 0 AW March 10, 1953 Filed Aug. 17, 1948 G. STEINGRUBERWINDOW SASH BALANCE 3 Sheets-Sheet 5 NTOR.

Patented Mar. 10, 1953 WINDOW SASH BALANCE George Steingruber, Atlanta,Ga. Minnie Baas Steingruber, executrix of said George Stein gruber,deceased Application August 17, 1948, Serial No. 44,679

11 Claims. (01. 16-198) The present invention relates to balancing meansfor sliding window sashes and the like, and more particularly, to animproved window sash balance of the spring-operated type.

While spring-operated window sash balances are not new, generallyspeaking, they have never been extensively adopted or received generalapproval of the public or the building trade. This lack of commercialsuccess has been largely due to the numerous practical disadvantages anddefects inherent in all the balancing devices of this type which haveheretofore been proposed, and especially due to the tendency of frequentbreakage of the springs.

I have found that in the use of coil springs which are wound upsufficiently tight to create a torque of such magnitude as to be capableof balancing the weight of a window sash, the frequent winding andunwinding of the spring incident to raising and lowering of the sash,soon causes the spring to break if the spring is anchored in a fixedposition at its opposite ends, as is the common practice. In addition,such springs tend to buckle and assume a wavy form longitudinally of thecoil, when wound tightly, with consequent loss of power, increasedfrictional contact with adjacent parts or surfaces,

and other impairments.

It is the primary object of the present invention to provide a simpleand effective window sash balance which eliminates the difficultiesand'defects just referred to, and which may be applied to single ordouble-hung window sashes of practically any type of windowconstruction, whether of wood or of metal, and irrespective of the sizeand/or weight of the sash.

According to this invention, my sash balance comprises a rotatable shaftabout which is wound a coil spring of appropriate size and length,commensurate with the weight of the sash which is to be balancedthereby, one end of said spring being anchored to the shaft for rotationtherewith incident to raising and lowering of the sash,

and the other end of the spring being connected to a movable anchorwhich is free to move axially relative to the spring responsive towinding and unwinding thereof.

A further object of the invention is to provide an improved sash balancemechanism which may be quickly and easily attached to or detached fromwindow sashes through means of thin, flexible cables or bands ofstainless steel or the like, which occupy little space and areinconspicuous when installed, yet possessed of great strength.

A still further object of the invention is to provide a sash balancemechanism which includes means for locking and releasing aspring-controlled balance shaft, at will, whereby to facilitate initialwinding or adjustment of the spring preliminary to installation of thebalance mechanism in a window structure, or to preserve and maintain theparts of the mechanism in a condition of rest during removal of themechanism for purposes of adjustment or repair.

Other and further objects and advantages of the invention will behereinafter described and the novel features thereof defined in theappended claims.

In the drawings: 7,

. Figure l is a view partly in horizontal section and partly in topplan, of a metal window structure of the .double-hungvertically slidingsash type, showing a typical application of my improved spring-operatedsash balance;

Figure 2 is a fragmentary vertical sectional view as taken on the line2-2 of Figure 1, with one of the sashes and certain parts of the sashbalance mechanism shown in elevation;

Figure 3 is a vertical sectional view through the complete windowstructure as taken on the line 3-3 ofFigure 2, transversely to the planeof the window, and more particularly showing the balanced suspension ofboth sashes by the respective separate spring-operated sash balancingmechanisms located at the top of the Window frame and connected to thesashes by flexible, thin stainless steel bands or cables wound aboutdrums on the spring-controlled balance shafts, with the free ends of thebands anchored to the upper edges of the respective sashes;

view taken on the line 66 of Figure 2, and showing the balance shaftlooks or clamps;

Figure 7 is an enlarged vertical sectional view through one of the cableor band drums on one of the balance shafts, and particularly showing themanner of connecting the inner end of the band to the drum;

Figure 8 is a fragmentary vertical sectional view as taken on the line88 of Figure 1;

Figure 9 is an enlarged perspective view of one of the balance shaftguides or supports; and

Figure is a fragmentary perspective View of the base plate or frame ofthe sash balance mechanism.

Like reference characters designate corresponding parts in the severalfigures of the drawings, wherein my improved window sash balancemechanism i shown in a form which is more particularly suitable forapplication to metal win dow structures of the double-hung, verticallysliding sash type. It is to be understood, however, that the balancemechanism is not limited to use with the specific type of windowconstruction illustrated in the drawings, but is equally applicable towindow structure of wood, or partly of ,wood and partly of metal, aswell as to other all-metal structures.

According to the construction as illustrated in the drawings, it will beseen that the window structure generally conforms to that dis-closed inmy co-pending application Serial No. 768,179, filed August 12th, 1947,now abandoned. These structures are characterized by the utilization ofmetal' extrusions of aluminum or the like which are assembled togetherto provide a generally rectangular frame designated I, of appropriatesize, the frame including a sill 2 extending transversely across thebottom thereof, and a pair of upright members of generally channel-formwhich are rigidly attached at their lower ends to the respectiveopposite ends of the sill 2, the upright members being designated 3, 3and forming the sides of the window frame. The attachment of the members3, 3 to the sill 2 may be made. in any suitable manner, but preferablyby means of an anchor bolt 4 extending upwardly through the sill 2 nearthe end thereof, and terminating at its upper end in a hook 5 whichengages in an opening 6 formed in the upright. By. tightening the nut lon the threaded lower end 8 of the anchor bolt 4, the upright 3 will befirmly and rigidly anchored to the sill, as more particularly describedand illustrated in my 00- pending application above referred to.

Similarly attached by corresponding anchor bolts 4 to the upper end ofthe uprights 3, 3 is a base plate generally designated 9, said baseplate forming a supporting frame for the sash balance mechanismhereinafter described, as well as forming the head of the window frame,said base plate 9 extending transversely across the upper end of themembers 3, 3, as shown in Figure 2.

Suitably attached at the center of the inner face of each upright 3, asby means of screw fastenings I0, is a parting strip II, said partingstrips extending vertically at each side of the window frame from thesill 2 to the base plate 9 at the upper end of the window frame. Theseparting strips may also have the form of extruded channels of aluminumor other metal and coact with stop strips I2 at the front and back'faces of the window frame to form guideways or channels in which thewindow sashes, generable in the usual manner of a double-hung window. Acorresponding parting strip I5 extends transversely across the lowerface of the base plate 9 at the upper end of the window frame, in thplane of the parting strips II, II, this parting strip I5 being eitherformed as an integral part of the base plate 9, as shown in thedrawings, or formed separately and attached to the base plate, whicheveris preferred.

The sashes l3 and I4 may be of any desired construction, but preferablyare of the type as disclosed in my co-pending application hereinbeforereferred to, the sash I3 being the lower sash, and the sash I4 being theupper sash when the window is closed. The bottom edge of the sash l3 andthe top edge of the sash I4 are each preferably provided with aresilient sealing member I5 such as a rubber or other sealing stripwhich is seated in a flanged mounting plate I6 suitably attached to theedge of the sash, as by means of screw fastenings l1. Attached by screwfastenings I8 to the upper edge of the sash I3 is a plate I9 whichoverhangs the face of the sash next to the sash I4, as best shown inFigure 3, the overhanging edge of the plate l9 forming a meeting railand terminating in a downwardly bent flange 20 which engages a rubber orother sealing strip 2| mounted in a channel 22 extended across theadjacent face of the sash I4 near the lower nd of the latter, suchengagement being effected when the sashes are closed, to prevent air andthe elements of the weather from entering between the sashes. As shownin Figure 2, a pivoted cam lock 23 is provided to permit the sashes tobe locked in their closed positions, when desired, such lock serving toforce the sealing strips l5 tightly against the window frame, and theflanged edge 20 of the meeting rail I8 tightly against the sealing strip2!, when the cam lock 23 is manipulated to its locking position in theconventional manner.

It will be seen from the drawings that the upper side of the base plate9 at the upper end of the window frame has a pair of spring-controlledbalance shafts designated 24 and 25 rotatably mounted thereon, therebeing one of said shafts for each of the respective window sashes I3 andI4. Each shaft is journaled in a plurality of brackets generallydesignated at 26, there preferably being four such brackets for eachshaft, a best shown in Figures 1 and 2. The brackets may all beidentical with each other and preferably have the form of a U- shapedmember which includes a flat plate 21 at the bottom thereof, theopposite ends of the plate being bent upwardly so as to provide twospaced end walls 28, 28, each having an opening 23 therethrough forreceiving the balance shaft. In order to mount the brackets 23 on thebase plate 9, the upper side of th base plate is provided with two setsof flanges respectively designated 30 and 3!, the flanges being parallelto each other and extending length-wise of the plate 9 from end-to-endthereof. As will be best seen from Figure 10, the free edges of each setof flanges are turned inwardly in opposed relation to each other and arespaced above the upper surface of the plate 9, thereby forming two waysrespectively designated 32 and 33 running parallel to each other acrossthe plate from end-toend. The brackets 26 may thus be assembled on theplate 9 by sliding the same into the ways 32 and 33 from either endthereof, and when so assembled, the bottom plate; 21; ofeach bracketseats fiat against the upper surface of the plate swith the oppositemarginal edges of the bottom plate disposed beneath the inwardly turnedflanges 33 or 3i, as th case may be, so as to prevent the brackets 26from rocking, twisting or otherwise moving out of alignment in therespective ways 32 and 33. The opposite edges of each end wall 28 ofeach bracket are notched, as at 34, 34, as best shown in Figure 9, toslidably receive the inwardly turned flanges 33 or 3| and thus permitassembly of the brackets 26 in the respective ways of the plate 9.

When the brackets 26 have been assembled in the ways 32 and 33 in themanner above described, they are arranged in spaced relation to eachother as shown in Figures 1 and 2 of the drawings. One of the bracketsis disposed adjacent to each end of the balance shaft 24, and acorresponding bracket is disposed adjacent to each end of the balanceshaft 25, all of these end brackets being suitably anchored to the plate9 so as to always remain in a fixed position. For

convenience and simplicity of manufacture, an-

chorage of these end brackets may be accomplished by providing theopposite edges of thebottom plate 2'! of each bracket with a notch orrecess 35, and after the brackets have been located in the properpositions in the respective ways 32 and 33, the flanges 3B and 3| aredepressed or deformed as by means of a punch or other suitable tool,into the respective notches 35, thereby positively interlocking thebrackets 26 with the plate 3 to preclude any displacement of th bracketsendwise in the ways. Thereafter, if it is desired to release thebrackets 26 to permit their removal from the plate 9 for purposes ofreplacement or repair of the sash balance mechanism, it is onlynecessary to force upwardly the depressed portions of the flanges 30 and3! so as to free the same from the notches 35. This operation can beaccomplished by means of a screwdriver or other pointed tool.

Between the end brackets of the respective balance shafts, and locatedsubstantially midway of each balance shaft but in spaced relation toeach other are two other brackets 26, one of which is anchored to theplate 9, as by depressing the flanges 36 and 3| into the notches 35 ofthe respective bottom plates 21, as indicated at 36 in Figures 1 and 6,while the other bracket is left free to slide in its way. Between thesetwo intermediate brackets and encircling the central portion of eachbalanc shaft is a coil spring 31,

I there being one coil spring for each balance shaft,

and the opposite ends of the respective coil springs abutting againstthe opposing end walls 28 of the respective intermediate brackets 26. Bythis arrangement, the coil springs 3'! always tend to urge the freelymovabl intermediate bracket 26 away from the fixed r anchoredintermediate bracket. At the opposite side of the intermediate freelymovable bracket on each balance shaft, 2, second coil spring 36 isloosely mounted on the balance shaft. One end of this coil spring isanchored to the adjacent end wall 26 of the freely movable intermediatebracket 26, as by hooking the end of the spring through two smallapertures 36 formed in this bracket, while the opposite end of the coilspring 33 is passed diametrically through a sleeve 40 and through thebalance shaft which is provided with a diametrical opening 41therethrough, as best shown in Figure 8. The sleeve 43 is disposed onthe balance shaft adjacent to the fixed end bracket 26 at the corresponding end of the spring 38, and the sleeve 46 tends 'to hold thespring'38 in concentrically 75 turns as are necessary to permit verticalmove- 6 spaced relation to the balance shaft, thereby minimizingfriction or drag of the spring on the shaft.

It will be understood from the foregoing that the spring 38 on eachbalance shaft is anchored at one end to the shaft and at the other endto the freely movable intermediate bracket 26. Accordingly, by rotatingthe balance shaft, the spring 38 will be wound or unwound, depending onthe direction of rotation of the balance shaft, while the freely movablebracket 26 is caused to slide on the balance shaft so as to always urgethe coils of the spring 28 closely together as the length of the springshortens during unwinding and lengthens during winding thereof. It isthis arrangement of the spring 38 and the movable intermediate bracket26 which is yieldingly urged toward the spring 38 by the spring 31,which prevents breaking of the spring 38 such as would occur if themovable intermediate bracket 26 were anchored in a fixed position. Inaddition, the arrangement as above described always maintains the coilsof the spring 38 close together and in axial alignment with each other,thereby avoiding any tendency of this spring to become distorted ordeflected to one side or the other, as commonly referred to ascaterpillaring. The elimination of such distortion of the springprevents any tendency of the spring to impart a frictional drag to thebalance shaft, as well as reduction of the stored power or torque of thespring by contact with the surrounding parts of the frame or othermechanism.

In order to transmit the balancing force of the springs 38 and balanceshafts 24 and 25 to the window sashes l3 and I4, it will be observedfrom the drawings that each balance shaft is provided at its oppositeends with a flanged pulley or drum 42. Each end of each balance shaft isslotted as at 43, with the slot extending inwardly from the end of theshaft to the inner side of the drum or pulley 42. The central portion ofeach drum 42, that is, the portion lying between the flanges 44, is alsoslotted so that when this slot, designated 45, is registered, with theslot 43 in the shaft, the free end of a band or cable 46 can be insertedthrough both slots 45 and 43, as shown in Figures '7 and 8, for thepurpose of anchoring the free end of the cable or band 46 to the balanceshaft on which the drum or pulley 42 is mounted. At the same time, theinserted end of the band or cable 46, which preferably hasthe form of arelatively thin, flexible, stainless steel band, serves to key thepulley 42 to the balance shaft, without the aid of any spe cial key orother fastening instrumentalities. Due to the thinness of the stainlesssteel band 46, it is desirable to double the end of the band, as clearlyshown in Figure 7, before inserting the same through the slots 45 and43, thereby strengthening the connection between the band and thebalance shaft, as well as between the pulley and the balance shaft. Dueto the absence of any screws or other connecting instrumentalitiespassing through the flexible band, break age of the band at the anchoredend thereof is minimized, and at the same time, the band can be quicklyconnected and disconnected at will, as well as the pulley or drum, incase it is necessary or desirable to remove the band and the pulley ordrum from the balance shaft for purposes of adjustment or repair of anyparts of the balance mechanism.

Each band or cable 46 is wrapped around the pulley or drum 42 for asufficient number of ment of the respective window sashes in the windowframe to which, the opposite. ends of the cables or bands 46 areconnected or anchored as shown in FiguresZ and 3 of the drawings. Thelatter connections. are also preferably made without any screws orfastenings penetrating the bands or cables, as by suitably slotting theopposite ends of theupper faces of the respective window sashes l3. andHi to receive the bands. therein in the manner of a looped anchor, asmore particularly shown in Figure 3 of the drawings'. It is to beunderstood, however, that the details of these anchor connections arenot material to the, present invention, since any suitable type ofanchoragemay be employed to anchor the ends of therespective cables orhands 46 to the window sashes. Due to the thinness of the bandsorcables, they occupy little space and are inconspicuous, yet possessedof ample strength to support the weight, of the window sashes ofpractically any type or construction, whether of wood or of metal, whichwould ordinarily be required practice. If desired, the parting strips lI may be recessed slightly at their opposite. f c s. a n i a ed at H inFigure 2, so that t e able or ban s 46. W i in the recesses which willaid in holding the bands in alignment with the drums or pulleys on whichthey are wound, as the sashes are raised and lowered in the windowframe.

Itwill be obvious that before the cables or bands. 46 are, connected tothe window sashes l3 and I4, it is necessary to. wind the springs 38Q11: the respective balance shafts 24 and 25 to an extent sufficient tosupport. the weight of the window sashes. In their wound condition, thesprings, 38 are foreshortened and the indiidual coils thereof willcloseup when the spring is fully woundso that the individual coils ofeach spring abut. against each other. In order to hold the springs in a.wound condition. while the cables; or hands 46 are connected to thedrums orpulleys 42 and to the window sashes, brake meansor clamps are.provided for the respective balance.- shafts 24 and 25', as indicatedat. 4"! in Figures 1' and 6. Each brake means or clamp 4! has the formof a strap or band of metal which extends about the balance shaft and isanchored at one end in any suitable manner to the-upper face of thebottom plate 21 of one-of the end brackets 26', as indicated at 43. Theopposite end of the band or strap is provided with a threaded apertureto receive an adjusting screw 49 which is threadedly engaged with theaperture and loosely extends through the plate 9'and the bottom plate2-! of the end bracket 26, with the head of the screw 49 accessible atthe top of the window frame when the window sashes are pulled down topermit the screws to be engaged by a screwdriver. The end of the strapor band which is threadedlyengaged with the screw 49 terminates somewhatabove the bottom plate 21 of the bracket 26 so that by tightening thescrew 49, the stra or band will grip or clamp about the balance shaftand hold it stationary until the balance mechanism has been connected bythe cables or bands 46 to the window sash, after which the, screws 49must be loosened to permit the balance shafts 24 and r 2,5 to, turnfreely as the. respective window sashes i3 and M are raised and lowered.When wound, the springs 38 will exertv a suflicient torque upon thebalance shafts to balancev the window sashes in any position to, whichthey are moved within the limits. of, their vertical adjustments in thewindow fr me, while offering no app eciable resistance to either upwardor downward movement of the sashes.

When the balance mechanism is incorporated in a metal window structureso as to form a part of the window frame, as shown by way ofillustration in the drawings, a cover or housing 50 is mounted on theplate 9 so as to enclose the respective balance mechanisms as best shownin Figures 3, 4 and 6, said cover being suitably attached to the plate9, as by means of the anchor bolts 8 which extend through the centraldepressed portion of the cover, as indicated at 5!, in which the upperends of the bolts 8 and nuts I lie and terminate below the upper edge ofthe cover, thereby eliminating any projections which would interferewith the hanging or mounting of the. window in an opening of a buildingstruc ture.

If the balance mechanism is to be applied to an existing windowstructure, either of wood or of metal, as a separate attachment,therefor, it will be obvious that the plate 9 may be modified by theprovision of upwardly extended flanges along its opposite edges to forma channel-like housing which is open at its upper side, and which may bescrewed or otherwise secured against the head of the window frame.

Other changes and alterations may be made without departing from thespirit of the invention as defined in the appended claims.

I claim:

1. A window sash balance mechanism of the class described for windowstructures in which a window sash is vertically slidable in a windowframe, comprising a spring-controlled balance shaft rotatablymounted atthe top of the win,- dow frame and transversely extended thereacrossabove the window sash, means for suspending the window sash from thebalance shaft, with the window sash balanced by the spring-controlledbalance shaft, and means frictionally engageable with. said balanceshaft and operable and releasable at will for restraining saidbal'ancershaft against rotationl 2., A. spring-controlled balancemechanism, comprising av balance shaft rotatably mounted on a base andhaving means for connecting the shaft to arr-object to be balanced, atorque spring of helically-coiled form encircling said: shaft, and hayinon end of th p n connected to said shaft, a pressure plate. slidablymounted on, said base andabutting the opposite end of said spring, withthe latter end of said spring connected to said pressure plate, andmeans acting on; said pressure plate for yieldablyurging the same in adirection tending to. maintain the, coils of the torque springrelatively close to. each other at all times during winding andunwinding ofthe torque spring according to the direction of rotation ofthe balance shaft 3. A spring-controlled balance; mechanism, comprisinga balance shaft rotatably mounted on a base and having means forconnecting the shaft to an object to be balanced, a torque spring ofhelically coiled form encircling said shaft. and having,- one end ofthe. spring connected to said shaft, a pressure plate slidably mountedon said baseand abutting the opposite end of said spring, with thelatter end of said spring connected to said pressure plate, and meansacting on said pressure plate for yieldably urging the same in adirection tending to maintain. the coils of the torque spring relativelyclose to each other at all times. during, winding and unwinding, of thetorque spring according to the direction of rotation of the balanceshaft, said last-named means comprising a second spring of helicallycoiled form encircling said balance shaft, said second spring beingnormally compressed and having one of its ends engaging the pressureplate at the side opposite to the torque spring aforesaid, and theopposite end of the second spring engaging a stationary abutment on saidbase.

4. A window sash balance mechanism of the class described for windowstructures in which a window sash is vertically slidable in a windowframe, comprising a supporting base member adapted to be mounted at thetop of said window frame and transversely extended thereacross, abalance shaft rotatably mounted on said base member and transverselyextended thereacross above the window sash, a pair of flexible cablesfixed to the respective opposite ends of the balance shaft so as to bewound thereon and unwound therefrom upon rotation of the balance shaftin opposite directions, said cables being connected at their oppositeends to the window sash, a coil spring encircling the balance shaft andhaving one of its ends fixed to the balance shaft, said coil springbeing wound to an extent which is sufficient to exert a torque upon thebalance shaft capable of balancing the window sash and sustaining thewindow sash in any position to which it is slidably moved in the windowframe, and an anchor member slidably mounted on said base memberaforementioned at the opposite end of the coil spring aforesaid andconnected to the latter end of the spring, said anchor member beingfreely movable towards and away from the first-mentioned end of thespring which is connected to the balance shaft, responsive to windingand unwinding of the spring incident to vertically sliding movements ofthe window sash, said flexible cables having the form of thin, stainlesssteel bands, drums fixed to the respective opposite ends of the balanceshaft and on which the respective bands are adapted to be wound andunwound, each end of said shaft and its corresponding drum being axiallyslotted to receive an end of one of the hands when the shaft slots andthe drum slots are registered with each other, whereby to anchor theends of the bands to the balance shaft and to the drums, and tosimultaneously key the a window sash is vertically slidable in a windowframe, comprising a supporting base member adapted to be mounted at thetop of said window frame and transversely extended thereacross, abalance shaft rotatably mounted on said base member and transverselyextended thereacross above the window sash, a pair of flexible cablesfixed to the respective opposite ends of the balance shaft so as to bewound thereon and unwound therefrom upon rotation of the balance shaftin opposite directions, said cables being connected at their oppositeends to the window sash, a, coil spring encircling the balance shaft andhaving one of its ends fixed to the balance shaft, said coil springbeing wound to an extent which is sufficient to exert a torque upon thebalance shaft capable of balancing the window sash and sustaining thewindow sash in any position to which it is slidably moved in the windowframe, and an anchor member slidably mounted on said base memberaforementioned at the opposite end of the coil spring aforesaid andconnected to the latter end of the spring, said anchor member beingfreely movable towards and away from the first-mentioned end of thespring which is connected to the balance shaft, responsive to windingand unwinding of the spring incident to vertically sliding move-- mentsof the window sash, said slidable spring anchor member having the formof a pressure plate and being yieldingly urged against the end of thecoil spring which is connected thereto so as to constantly maintain thecoils of the coil spring in close relation to each other as the coilspring shortens and lenthens during winding and unwinding thereof by thevertical sliding movements of the window sash and consequent rotation ofthe balance shaft.

6. A window sash balance mechanism of the class described for windowstructures in which a window sash is vertically slidable in a windowframe, comprising a supporting base member adapted to be mounted at thetop of said window frame and transversely extended thereacross, abalance shaft rotatably mounted on said base member and transverselyextended thereacross above the window sash, a pair of flexible cablesfixed to the respective opposite ends of the balance shaft so as to bewound thereon and unwound therefrom upon rotation of the balance shaftin opposite directions, said cables being connected at their oppositeends to the window sash, a coil spring encircling the balance shaft andhaving one of its ends fixed to the balance shaft, said coil springbeing wound to an extent which is sufficient to exert a torque upon the,balance shaft capable of balancing the window sash and sustaining thewindow sash in any position to which it is slidably moved in the windowframe, and an anchor member slidably mounted on said base memberaforementioned at the opposite end of the coil spring aforesaid andconnected to the latter end of the spring, said anchor member beingfreely movable towards and away from the first-mentioned end of thespring which is connected to the balance shaft, responsive to windingand unwinding of the spring incident to vertically sliding movements ofthe window sash, said slidable spring anchor member having the form of apressure plate and being yieldingly urged by a separate axiallycompressed coil spring encircling the balance shaft at the side of thepressure plate opposite'to the first-mentioned coil spring, against theend of the coil spring which is connected thereto so as to constantlymaintain the coils of the first coil springs in close relation to eachother as the spring shortens and lengthens during winding and unwindingthereof by the vertical sliding movements of the window sash andconsequent rotation of the balance shaft.

'7. A window sash balance mechanism of the class described for windowstructures in which a window sash is vertically slidable in a windowframe, comprising a supporting base member adapted to be mounted at thetop of said window frame and transversely extended thereacross, abalance shaft rotatably mounted on said base member and transverselyextended thereacross above the window sash, a pair of flexible cablesfixed to the respective opposite ends of thebal ance shaft so as to bewound thereon and unwound therefrom upon rotation of the balance shaftin opposite directions, said cables being con nected at their oppositeends to the window sash, a coil spring encircling the balance shaft andhaving one of its ends fixed to the balance shaft,

said coilspring being wound to an extent which is sufiicient to exert atorque upon the balance shaftcapable of balancing the window sash andsustaining the window sash in any position to which it is slidably movedin the window frame, and an anchor member slidably mounted on said basemember aforementioned at the opposite end of the coil spring aforesaidand connected to the latter end of the spring, said anchor memberbeingfreely movable towards and awayfrom the first-mentioned end of thespring which is connected" to the balance shaft, responsive to windingand unwinding of the spring incident to vertically sliding movements ofthe window sash, said balance shaft being journaled in a plurality ofbrackets which are assembled on the base member, said base member havinga transversely extended way running across the head of the window frame,with the brackets slidable in said way from either end thereof toposition the brackets in positions to support the balance shaft at itsopposite ends and at an intermediate point of the balance shaft. 1

V 8. A. window sash balance mechanism of the class described for windowstructures in which a windowsash is vertically slidable in a windowframe, comprising a supporting base member adapted to be mounted at thetop of said window frame and transversely extended thereacross, abalance shaft rotatably mounted on said base member and transverselyextended thereacross above the window sash, a pair of flexible cablesfixed to the respective opposite ends of the balance shaft so as to bewound thereon and unwound therefrom upon rotation of the balance shaftin opposite directions, said cables bein connected at their oppositeends to the window sash, a coil spring encircling the balance shaft andhaving one of its ends fixed to the balance shaft, said coil springbeing wound to an extent which is sufficient to exert a torque upon thebalance shaft capable of balancing the window sash and sustaining thewindow sash in any position to which it. is slidably moved in the windowframe, and an anchor member slidably mounted on said base member.aforementioned at the opposite end of the coil spring aforesaid andconnected to the latter end of the spring, said anchor member beingfreely movable towards and away from the first-mentioned end of thespring which is connected to the balance shaft, responsive to windingand unwinding of the spring incident to vertically sliding movements ofthe window sash, said balance shaft being journaled in a plurality ofbrackets which are assembled on the base memher, said base member havinga transversely extended way running across the head of the win-v dowframe, with the brackets slidable in said way from either end thereof toposition the brackets in positions to support the balance shaft at itsopposite ends and at an intermediate point of the balance shaft, each ofsaid brackets having a notch in at least one edge thereof to permitanchorage of the brackets in their fixed positions on the base bydeforming the base at the notches to depress the same into interlockingrelation with the notches.

9; A window sash balance mechanism of the class described for windowstructures in which a window sash is vertically slidable in a windowframe, comprising a supporting base member adapted to be mounted at thetop of said window frame and transversely extended thereacross, abalance shaft rotatably mounted on said base member and transverselyextended thereacross above the Window sash, a pair of flexible cablesfixed to the respective opposite ends of the balance shaft so as to bewound thereon and unwound therefrom upon rotation of the balance shaftin opposite directions, said cables being connected at their oppositeends to the window sash, a coil spring encircling the balance shaft andhaving one of its ends fixed to the balance shaft, said coil springbeing wound to an extent which is sufficient to exert a torque upon thebalance shaft capable of balancing the window sash and sustaining thewindow sash in any position to which it is slidably moved inthe windowframe, and an anchor member slidably mounted on said base memberaforementioned at the opposite end of the coil spring aforesaid andconnected to the latter end of the spring, said anchor member beingfreely movable towards and away from the first-mentioned end of thespring which is connected to the balance shaft, responsive to windingand unwindingof the spring incident to vertically sliding movements ofthe window sash, said balance shaft being journaled in a plurality ofbrackets which are assembled on the base member, said base member havinga transversely extended way running across the head of the window frame,with the brackets slidable in said way from either end thereof toposition the brackets in positions to support the balance shaft at itsopposite ends and at an intermediate point of the balance shaft, and theslidable anchor for the coil spring having a form corresponding to thebrackets aforesaid, with the balance shaft journaled therein and beingfreely slidable on the balance shaft in spaced relation to theintermediate bracket.

10. A window sash balance mechanism of the class described for windowstructures in which a window sash is vertically slidable in a windowframe, comprising a supporting base member adapted to be mounted at thetop of said window frame and transversely extended thereacross, abalance shaft rotatably mounted on said base member and transverselyextended thereacross above the window sash, a pair of flexible cablesfixed to the respective opposite ends of the balance shaft so as to beWound thereon and unwound therefrom upon rotation of the balance shaftin opposite directions, said cables being connected at their oppositeends to the window sash, a coil spring encircling the balance shaft andhaving one of its ends fixed to the balance shaft, said coil springbeing wound to an extent which is sufilcient to exert a torque upon thebalance shaft capable of balancing the window sash and sustaining thewindow sash in any position to which it is slidably moved in the windowframe, and an anchor member slidably mounted on said base memberaforementioned at the opposite end of the coil spring aforesaid andconnected to the latter end of the spring, said anchor member beingfreely movable towards and away from the first-mentioned end of thespring which is connected to the balance shaft, responsive to windmg andunwinding of the spring incident to vertically sliding movements of theWindow sash, said balance shaft being journaled in a plurality ofbrackets which are assembled on the base member, said base member havinga transversely extended way running across the head of the wind-owframe, with the brackets slidable in said way from either end thereof toposition the brackets in positions to support the balance shaft at itsopposite ends and at an intermediate point of the balance shaft, and theslidable anchor for the coil spring having a form corresponding to thebrackets aforesaid, with the balance shaft journaled therein and beingfreely slidable on the balance shaft in spaced relation to theintermediate bracket, and a second coil spring encircling the balanceshaft and interposed between the intermediate bracket and the slidableanchor bracket aforesaid for yieldably urging the slida-ble anchorbracket against the adjacent end of the first-mentioned coil spring.

11. A window sash balance mechanism of the class described for windowstructures in which a window sash is vertically slidable in a windowframe, comprising a supporting base member adapted to be mounted at thetop of said window frame and transversely extended thereacross, abalance shaft rotatably mounted on said base member and transverselyextended thereacross above the window sash, a pair of flexible cablesfixed to the respective opposite ends of the balance shaft so as to bewound thereon and un-,

wound therefrom upon rotation of the balance shaft in oppositedirections, said cables being connected at'their opposite ends to thewindow sash, a coil spring encircling the balance shaft {and having oneof its ends fixed to the balance shaft,"

said coil spring being wound to an extent which is suflicient to exert atorque upon the balance shaft capable of balancing the window sash andsustaining the window sash in any position to which it is slidably movedin the window frame, and an anchor member slidably mounted on said basemember aforementioned at the opposite end of the coil spring aforesaidand connected to the latter end of the spring, said anchor member beingfreely movable towards and away from the first-mentioned end of thespring which is connected to the balance shaft, responsive to windingand. unwinding of the spring incident to vertically sliding movements ofthe window sash, said balance shaft being provided with releasableclamping means operable at will for holding the balance shaft againstrotation under the influence of the torque of the coil spring, saidclamping means having the form of a band embracing the balance shaft andoperable by a screw accessible from the inner face of the window frameto tighten and loosen the band about the balance shaft to respectivelyclamp or release the shaft.

GEORGE STEINGRUEER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 758 Kimballe May 30', 1838329,409 Ormsby Oct. 27, 1885 416,207 Bastian Dec. 3, 1889 866,278Hemenway Sept. 17, 1907 2,112,650 Girard Mar. 29, 1938 2,190,098Dautrick Feb. 13, 1940 2,314,015 Parsons Mar. 16, 1943

